The present disclosure relates generally to a junction barrier Schottky diode (JBS) and, more specifically, to a junction barrier Schottky diode with higher reverse blocking voltage.
Integrated circuits have generally included Schottky diodes for power applications. Schottky diodes tend to be very leaky at high reverse bias and high temperatures. Circuit designers have used junction barrier Schottky diodes to provide a solution to the leaky Schottky diodes. This combination provides a Schottky-like forward conduction and PN diode like reverse blocking of voltage. It basically includes a PN junction and a Schottky junction diode in parallel. Although this has solved the leakage problems, the JBS diodes built to date have historically had reverse blocking voltages in the range of 30 volts. There is a need to provide an improved JBS diode with substantially greater reverse blocking voltage.
The present junction barrier Schottky diode has an N-type well having a surface and a first impurity concentration; a p-type anode region in the surface of the well, and having a second impurity concentration; and an N-type cathode region in the surface of the well and horizontally abutting the anode region, and having a third impurity concentration. A first N-type region vertically abuts the anode and cathode regions, and has a fourth impurity concentration. An ohmic contact is made to the anode and a Schottky contact is made to the cathode. The fourth impurity concentration is less than the first, second and third impurity concentrations.
The cathode and anode regions have substantially the same depth. The cathode and anode regions may be concentric. The cathode region may be between two spaced anode regions or the anode region may be between two spaced cathode regions.
The maximum impurity concentration of the anode region is below the surface. The fourth impurity concentration's maximum may be one order of magnitude less than the second impurity concentration's maximum, and the fourth impurity concentration's minimum is one order of magnitude less than the third impurity concentration's maximum. The second, third and fourth impurity concentrations are of a value to produce a diode having a reverse blocking voltage of at least 60 volts.
The N-type well may include a buried p-type region below and vertically abutting the first N-type region and having a fifth impurity concentration. The second, third, fourth and fifth impurity concentrations may be of a value to produce a diode having a reverse blocking voltage of at least 70 volts or at least 90 volts.
Although the junction barrier Schottky diode is generally used in integrated circuits, the present junction barrier Schottky diode may be a discrete device.
These and other aspects of the present disclosure will become apparent from the following detailed description of the disclosure, when considered in conjunction with accompanying drawings.